Digital Creations Zope 2.3.1 b1 and earlier contains a problem in the method return values related to the classes (1) ObjectManager, (2) PropertyManager, and (3) PropertySheet.
http://www.zope.org/Products/Zope/Products/Zope/Products/Zope/Hotfix_2001-02-23
http://www.redhat.com/support/errata/RHSA-2001-021.html
http://www.linux-mandrake.com/en/security/2001/MDKSA-2001-025.php3
http://www.debian.org/security/2001/dsa-043
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000382